diff --git a/.github/workflows/bazel.yml b/.github/workflows/bazel.yml
index 627993c811..cc3968d306 100644
--- a/.github/workflows/bazel.yml
+++ b/.github/workflows/bazel.yml
@@ -58,6 +58,7 @@ jobs:
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
           persist-credentials: false
 
       - name: Check rusty_v8 MODULE.bazel checksums
@@ -152,6 +153,7 @@ jobs:
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
           persist-credentials: false
 
       - name: Prepare Bazel CI
@@ -237,6 +239,7 @@ jobs:
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
           persist-credentials: false
 
       - name: Prepare Bazel CI
@@ -326,6 +329,7 @@ jobs:
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
           persist-credentials: false
 
       - name: Prepare Bazel CI
diff --git a/.github/workflows/blob-size-policy.yml b/.github/workflows/blob-size-policy.yml
index e7817a9f65..779198ee02 100644
--- a/.github/workflows/blob-size-policy.yml
+++ b/.github/workflows/blob-size-policy.yml
@@ -10,6 +10,7 @@ jobs:
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
           fetch-depth: 0
           persist-credentials: false
 
@@ -18,8 +19,8 @@ jobs:
         shell: bash
         run: |
           set -euo pipefail
-          echo "base=$(git rev-parse HEAD^1)" >> "$GITHUB_OUTPUT"
-          echo "head=$(git rev-parse HEAD^2)" >> "$GITHUB_OUTPUT"
+          echo "base=${{ github.event.pull_request.base.sha }}" >> "$GITHUB_OUTPUT"
+          echo "head=${{ github.event.pull_request.head.sha }}" >> "$GITHUB_OUTPUT"
 
       - name: Check changed blob sizes
         env:
diff --git a/.github/workflows/cargo-deny.yml b/.github/workflows/cargo-deny.yml
index 94967e7e79..f20d09e112 100644
--- a/.github/workflows/cargo-deny.yml
+++ b/.github/workflows/cargo-deny.yml
@@ -16,6 +16,7 @@ jobs:
       - name: Checkout
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
           persist-credentials: false
 
       - name: Install Rust toolchain
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 3754155912..a1c60acc26 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -14,6 +14,7 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
           persist-credentials: false
 
       - name: Verify codex-rs Cargo manifests inherit workspace settings
diff --git a/.github/workflows/codespell.yml b/.github/workflows/codespell.yml
index d4a8469a53..aaa15cf40d 100644
--- a/.github/workflows/codespell.yml
+++ b/.github/workflows/codespell.yml
@@ -20,6 +20,7 @@ jobs:
       - name: Checkout
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
           persist-credentials: false
       - name: Annotate locations with typos
         uses: codespell-project/codespell-problem-matcher@b80729f885d32f78a716c2f107b4db1025001c42 # v1.1.0
diff --git a/.github/workflows/rust-ci.yml b/.github/workflows/rust-ci.yml
index 52322913e5..75c5c33601 100644
--- a/.github/workflows/rust-ci.yml
+++ b/.github/workflows/rust-ci.yml
@@ -16,6 +16,7 @@ jobs:
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
           fetch-depth: 0
           persist-credentials: false
       - name: Detect changed paths (no external action)
@@ -64,6 +65,7 @@ jobs:
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
           persist-credentials: false
       - uses: dtolnay/rust-toolchain@a0b273b48ed29de4470960879e8381ff45632f26 # 1.93.0
         with:
@@ -82,6 +84,7 @@ jobs:
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
           persist-credentials: false
       - uses: dtolnay/rust-toolchain@a0b273b48ed29de4470960879e8381ff45632f26 # 1.93.0
       - uses: taiki-e/install-action@44c6d64aa62cd779e873306675c7a58e86d6d532 # v2.62.49
@@ -101,6 +104,7 @@ jobs:
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
           persist-credentials: false
       - uses: dtolnay/rust-toolchain@a0b273b48ed29de4470960879e8381ff45632f26 # 1.93.0
       - name: Install nightly argument-comment-lint toolchain
@@ -179,6 +183,7 @@ jobs:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         if: ${{ steps.argument_comment_lint_gate.outputs.run == 'true' }}
         with:
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
           persist-credentials: false
       - name: Run argument comment lint on codex-rs via Bazel
         if: ${{ steps.argument_comment_lint_gate.outputs.run == 'true' }}
diff --git a/.github/workflows/sdk.yml b/.github/workflows/sdk.yml
index cc26a4785a..0f9065941b 100644
--- a/.github/workflows/sdk.yml
+++ b/.github/workflows/sdk.yml
@@ -15,6 +15,7 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
           persist-credentials: false
 
       - name: Install Linux bwrap build dependencies
diff --git a/.github/workflows/v8-canary.yml b/.github/workflows/v8-canary.yml
index 50ec353c2e..6e71367d1f 100644
--- a/.github/workflows/v8-canary.yml
+++ b/.github/workflows/v8-canary.yml
@@ -42,6 +42,7 @@ jobs:
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
           persist-credentials: false
 
       - name: Set up Python
@@ -78,6 +79,7 @@ jobs:
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
         with:
+          ref: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.sha || github.sha }}
           persist-credentials: false
 
       - name: Set up Bazel